Do you know why soaps are slippery? Actually, the structure of a soap molecule is such that, in the presence of water, they tend to build up a thin, liquid-like-film at the surface of the soap, which allows objects to glide easily against each other. In fact, skating works on the same principle as well. A water film is created by melting ice under pressure of the skate. So now you know how and why your skates glide so easily on ice.